A method and apparatus for forming a crystalline semiconductor layer on a substrate are provided. A semiconductor layer is formed by vapor deposition. A pulsed laser melt/recrystallization process is performed to convert the semiconductor layer to a crystalline layer. Laser, or other electromagnetic radiation, pulses are formed into a pulse train and uniformly distributed over a treatment zone, and successive neighboring treatment zones are exposed to the pulse train to progressively convert the deposited material to crystalline material.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of treating a substrate, comprising: Identifying a first treatment zone; forming a molten area of the first treatment zone by exposing a surface of the first treatment zone to a first laser pulse, wherein the first laser pulse has a non-uniformity of less than about 5 percent; recrystallizing the molten area of the first treatment zone while exposing the first treatment zone to a plurality of laser pulses; identifying a second treatment zone; and repeating the forming a molten area and the recrystallizing the molten area with the second treatment zone, wherein the forming a molten area of each treatment zone further comprises exposing the surface of each treatment zone to a second laser pulse, and a duration between the first laser pulse and the second laser pulse is less than a time necessary for a portion of the molten area to refreeze, and wherein the first laser pulse and the second laser pulse have the same duration and intensity.
2. The method of claim 1 , wherein each pulse of the plurality of laser pulses has the same duration and intensity as the first laser pulse.
3. The method of claim 1 , wherein each pulse of the plurality of laser pulses has a duration or an intensity that is different from the first laser pulse.
4. The method of claim 1 , wherein the second treatment zone and the first treatment zone share a boundary.
5. A method of treating a substrate, comprising: Identifying a first treatment zone; forming a molten area of the first treatment zone by exposing a surface of the first treatment zone to a first laser pulse, wherein the first laser pulse has a non-uniformity of less than about 5 percent; recrystallizing the molten area of the first treatment zone while exposing the first treatment zone to a plurality of laser pulses, wherein each pulse of the plurality of laser pulses has a duration or an intensity that is different from the first laser pulse; identifying a second treatment zone; and repeating the forming a molten area and the recrystallizing the molten area with the second treatment zone, and wherein the forming a molten area of each treatment zone further comprises exposing the surface of each treatment zone to a second laser pulse, and a duration between the first laser pulse and the second laser pulse is less than a time necessary for a portion of the molten area to refreeze.
6. The method of claim 5 , wherein a duration between each pulse of the plurality of laser pulses is more than a time to freeze the portion of the first treatment zone.
7. The method of claim 5 , wherein each pulse of the plurality of laser pulses melts a portion of a recrystallized area.
8. The method of claim 5 , wherein the second treatment zone is adjacent to the first treatment zone.
9. The method of claim 5 , wherein each pulse of the plurality of laser pulses melts a portion of a recrystallized area and the second treatment zone is adjacent to the first treatment zone.
10. A method of treating a substrate, comprising: identifying a first treatment zone; forming a molten area of the first treatment zone by exposing a surface of the first treatment zone to a first group of one or more laser pulses and a second group of one or more laser pulses, wherein a power delivered by the second group of one or more laser pulses is higher than a power delivered by the first group of one or more laser pulses; recrystallizing the molten area of the first treatment zone while exposing the first treatment zone to a third group of one or more laser pulses, wherein a power delivered by the third group of one or more laser pulses is less than a power delivered by the first group of one or more laser pulses and a power delivered by the second group of one or more laser pulses; identifying a second treatment zone adjacent to the first treatment zone; and repeating the forming a molten area and the recrystallizing the molten area with the second treatment zone.
11. The method of claim 10 , wherein first one or more laser pulses are separated from the second one or more laser pulses by a rest duration, wherein the rest duration allows partial refreezing of the molten area before a subsequent pulse arrives.
12. The method of claim 10 , wherein the first group of one or more pulses is one pulse, the second group of one or more pulses comprises multiple pulses and the third group of one or more pulses comprises multiple pulses.
13. The method of claim 12 , wherein the multiple pulses of the second group of one or more pulses overlap in time.
14. The method of claim 13 , wherein the multiple pulses of the third group of one or more pulses are separated by a rest duration.
15. A method of treating a substrate, comprising: identifying a first treatment zone; forming a molten area of the first treatment zone by exposing a surface of the first treatment zone to a first plurality of laser pulses, wherein the pulses of the first plurality of laser pulses have an overlap factor between about 10 percent and about 40 percent; recrystallizing the molten area of the first treatment zone while exposing the first treatment zone to a second plurality of laser pulses, wherein each pulse of the second plurality of laser pulses melts a portion of a recrystallized area; identifying a second treatment zone adjacent to the first treatment zone; and repeating the forming a molten area and the recrystallizing the molten area with the second treatment zone.
16. The method of claim 15 , wherein each pulse of the first plurality of laser pulses has a duration between about 1 ns and about 50 ns.
17. The method of claim 16 , wherein each pulse of the first plurality of laser pulses has a duration between about 20 ns and about 30 ns.
18. The method of claim 15 , wherein each pulse of the first plurality of laser pulses delivers a power between about 10 7 W/cm 2 and about 10 9 W/cm 2 .
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February 7, 2014
December 9, 2014
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